In the past fuel rails were generally made by bonding a number of metal components together or by intricately machining each rail from a single block of metal stock. Attempts have been made to replicate the metal fuel rails in plastic but these attempts have not been overwhelmingly successful until now. Numerous obstacles had to be overcome to produce a molded plastic fuel rail having all of the required features. One major problem in producing a plastic fuel rail by injection molding processes involved the location of the fuel outlets from the rail barrel to the injector sockets. To provide maximum protection against the ingestion of fuel vapors, normally present in the top portion of the rail bore, into the fuel injectors, the fuel outlets should be located in the bottom portion of the rail body. Space limitations and other factors require the injector socket axes to be oriented at an acute angle relative to verticle. State-of-the-art injection molding practices did not provide a means for locating the rail-to-socket fuel outlets in the bottom of the rail body when the sockets were oriented at an angle to vertical. A related problem involved support for the elongated core pin for the fuel rail barrel when the socket core pins were placed off center to produce the aforementioned arrangement between the sockets and the rail body. Sound molding procedures dictated that the axes of the laterally disposed socket core pins be aligned with the axis of the barrel core pin so that the barrel core pin could rest on the centers of the socket core pins and thus be given adequate support during the plastic injection stage.
Another problem is that molded plastic items have a tendency to fail if certain areas are subjected even to minimal compressive loads for a prolonged period of time. Because of this trait it was difficult to provide a suitable structural arrangement for closing the core pin access opening located at one end of the rail body.
Accordingly, it is a general object of this invention to provide a high quality, durable fuel rail that can be readily and reliably molded.
It is a another object of this invention to provide a special configuration for a fuel rail which meets certain requirements and can be produced from plastic material by injection molding.
It is a another object of this invention to provide a molded fuel rail having a series of fuel injector sockets which communicate with the rail interior through apertures located in the bottom of the rail body and which are obliquely disposed relative to a vertical plane containing the rail axis.
It is yet another object of this invention to produce such a fuel rail having an end with a zero compressive load closure.